[time-nuts] Second FTS4060 shows Drift, is it me? Good Links
brooke at pacific.net
Mon Feb 6 13:14:08 EST 2006
Sorry for the bad links, here are good ones:
Today's plot = http://www.pacificsites.com/~brooke/pdf/sn1013_850_Drift2.pdf
s/n 1227 29 Apr 2005 plot =
Brooke Clarke wrote:
>A year ago I took apart the FTS4060 that was DOA (s/n 1013) because of
>rough shipping and used it to figure out most of the interconnect
>wiring. A few months ago I put it back together with the thought of
>selling it as a parts unit. But first powered it up and found that it
>now locked and seemed to be working so tried to set the C-field.
>For the last couple of weeks it has shown a parabolic plot like s/n
>1227, although this time the polarity is opposite that of s/n 1227 which
>also showed drift, but that may be a setup difference. A plot of s/n
>1227 is at: file:///C:/Webdocs/pdf/Cs_Drift0429.pdf
>The equation for s/n 1013 is:
> y = 2.7943x2 - 302.64x + 8969.4 and the quality of fit is
>R2 = 0.9088. The x-axis is in days and the y-axis is in ns.
>The first derivative of the equation has a first term of 2 * 2.7943 * x
>ns/day or +5.3E-14 seconds/seconds drift rate.
>Today's plot is at: file:///C:/Webdocs/pdf/sn1013_850_Drift2.pdf
>The current setup is:
>SR620 time interval counter doing 500 averages (500 seconds = 8 1/3
>Start from Motorola M12+T (9 ns jitter).
>Stop from FTS4060 1 MHz output.
>Manually enter into spreadsheet date and time of reading (usually not on
>the 8 1/3 minute change, just a random time) and counter value.
>For most of the test the SR620 was using it's internal oscillator and
>just recently I changed it to the PRS10 external standard but that does
>not seem to have made any difference.
>Is there something I'm doing wrong that would cause apparent drift?
>Thanks for any thoughts,
>Brooke Clarke, N6GCE
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
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